Usb spe-2kfa

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I just got around to hooking up my Flex 6700 and SPE-2KFA amp with SSDR 1.10 (beta). I was pleasantly suprised at how easy it was. I had some FTDI USB to serial adapters that I got off of Amazon a few years back. I wasn't sure if they were genuine FTDI, but I tried anyways. The Flex recognized it right away. Once I got the baud rate set up the SPE recognized the Flex as well and the SPE controls the RF power setting when the amp is in operate mode and resets it when the amp is in standby.

As I understand it, the ALC input on the Flex doesn't really work so we have to manually set the max power out using the feature of the amp.
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Mark Erbaugh

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Posted 3 years ago

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Joe WD5Y

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Mark,
I believe the alc function works on the flex. I use it with my amp and it seems ok. Somebody else may need to elaborate on this as well. The meter on smartsdr shows alc indication for sure. I know many operators do not prefer alc but I chose it's use as further protection.

73's
WD5Y
Joe
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Tim - W4TME, Customer Experience Manager

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The ALC does work on the FLEX-6000.  The max power setting was for the FLEX Series radios that do not have ALC.  However, the use of ALC in general, has been in debate because the delay between setting the ALC voltage and the power reduction of the exciter may be too long to prevent damage to some amps.  If the amp has internal protection mechanisms, those should be your first line of defense.
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Mark Erbaugh

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I ran a quick test. The ALC meter does indicate activity, but I didn't want to overdrive the amp, so I was afraid to crank the Flex power to full and see if the SPE ALC limits the power out. The SPE manual recommends running the drive level at full and letting the amp control the ALC. I like the extra protection of setting the max power out, so I'll use both.
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Gary

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This is in response to your statement re using the ALC on the SPE amps and Tim's saying the ALC does work.... I've noted that the SPE says the ALC signal can be as low as -11V whereas the hardware instructions for the Flex 6700 say not to go lower than -4V or damage might ensue... I've no reason to doubt what SPE is saying - so since you connected the two up were you just lucky or does the flex actually have protection against lower levels of ALC coming in? As I understand ALC it is nominally at its lowest level - so when not 'active' the SPE would be outputting -11V!

[its been a couple months since I looked at this in their respective manuals... I'm pretty sure the numbers are accurate... it seems strange that the Flex would say this - its so easy and cost pennies to clamp a signal so that neither the input nor itself is effected detrimentally.]

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Mark Erbaugh

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Thanks for the pointer on ALC level to the Flex. I just ran a test. As you increase the drive level, the SPE's ALC goes from 0 to -11v. Testing into a dummy load on, I noticed that once the ALC kicked in, it took the Flex a while to return to power, missing the next couple syllables. At this point, I've revised my hook up and disconnected ALC.

I guess the question for Flex and SPE users is connect ALC or not?
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Ria - N2RJ, Elmer

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Skip the ALC and let the amp control power via CAT. SPE's use of ALC with flex radios doesn't work properly. Using ALC to control drive power is an ugly hack that may or may not work. Wayne Burdick from elecraft has also recommended against it for the k3 and instead recommends setting drive power manually.
(Edited)
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Winston VK7WH

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Mark, have you tried connecting the SPE ALC to the Flex 6xxx ALC connectors via a 11/4 voltage divider? It would be interesting to know if this approach reduces the Flex ALC recovery time which could be causing the lost of the first few syllables you were experiencing.

Just a thought
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KY6LA - Howard, Elmer

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I have been running my SPE 2K=FA WITHOUT ALC for over 3 years with no issues whatsoever.

Albeit I use DDUTIL TO SET DRIVE LEVELS BY BAND.

Works perfectly.
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Gary

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The purpose of ALC isn't, at least as far as I'm concerned and I believe the designers, to give a general power control... its to avoid issues if one mistakenly has the rig set to too high power. I currently use my FTdx5000 with the 2K ... when using the amp the rig is generally set to class A and 35W or so ... however occasionally I run the rig barefoot and sometimes at its full power of 200W ... and then I will inevitability forget to turn the power down and enable the amp ... the ALC works great in this regard keeping the power to the point where the amp is fine (albeit too high output) ... I'll quickly see the power level and reduce power. Of course the amp needs to assume nothing and protect itself - but to me not using the ALC seems a bit silly.

That stated I don't know what this 'let the AMP control power via CAT" is - but would have to imagine the delays in it are just as onerous as using the ALC as is - maybe more so. The proper fix might be to figure out why the ALC might be not quite reactive enough and if it is indeed the 11/4 difference simply do a simply resistive divider with a clamp and get it to work fine. It seems to do a great job with the Yaesu.

 

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Gary

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Just to be sure .... what Flex says about ALC is this:

Please note this input is provided as a safety measure for external amplifiers

which is why I would recommend using it! Although indeed some amps don't implement it ... and contrary to Flex's statement

Almost all modern HF amplifier manufacturers discourage the use of ALC

THIS is what SPE says:

"This connection is highly recommended"

Why Flex chose not to clamp the input and allow a wider range (the SPE outputs -11, the Flex allows -4 max) by a few pennies worth of components is something I can't explain ... an oversight or someone taking the "ALC - BAD" thought process a bit too far ... if you're going to put it there do it fully!

The CAT control, as far as I can see, is not going to prevent overdriving the amp if one sets the power to a higher level... I've read through the 10.8 manual as well as the USB manual and haven't yet found anything that is interactive that knows when the amp is enabled or not and ensures the power level, with the amp on, is appropriate. If indeed the connection is interactive and the FLEX/SPE know together when the amp is enabled and know to reduce power to the 'amp - approved' level.. that would be great... THEN the ALC wouldn't be needed.

If I've missed it I apologize and would welcome the manual reference since I've yet to link the 2K to the 6700 but will in the future.

Gary


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Mark Erbaugh

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With the Flex USB cable connected to the SPE, the amp sets the power output of the Flex to whatever the operator programmed (by band) into the amp. If you try to change the power using SSDR, the amp changes it back. This should protect the amp from overdriving, but unfortunately also resets the power if you try to reduce the power level, so the only way I've found to reduce the power out is to reduce the setting in the amp. I think it would be better if the amp set just the max power out, but you could reduce when needed.
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Ria - N2RJ, Elmer

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SPE uses the ALC as a primary method of power control. Yes, you can set the power yourself to a low level and let ALC cut back if needed but the manual seems to say that just set your exciter to max and let the amp reduce it as needed. This to me is a gross misuse of ALC which as you correctly stated is supposed to be a safety feature to limit drive power. This is why radio manufacturers cringe at the thought of using ALC with an SPE amplifier.

CAT power control on the other hand simply sets a fixed drive power level that you set, per band and per output power level (low/mid/max). Once you switch the amp to "operate" it sets the power level via CAT and keeps it there. Once you go back to standby it returns to where you had it. So on standby I can use 100w from the exciter and with operate mode I get 2, 5 and 10 watts drive the amp, all automatically. It doesn't change real time with ALC. It stays at one level:
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Gary

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Ah - OK.... I hadn't seen that in the documentation. I was visiting someone else that has a 6500 yesterday and in the course of showing his station he did show me that if he set his amp in standby (an Elecraft KPA500) the 6500 changed the power level to 100W ... however he is using DDUtil for this. He agreed, although we're both still not 100%, or weren't, that it can or can't be done in SSDR. So you're saying SSDR alone will know when the amp is in standby and change the power back to some other setable level - correct?

If that is the case then indeed the ALC is not needed... HOWEVER - again - as a last resort protection method, knowing fair well that things can and do go wrong - if its there - I WOULD/WILL USE IT! Although the SPE amps are (almost) bullet proof I'd never want to hit them with high power without an ALC. So once again - I'd still say install the ALC line which brings us back to - why did they not design the input to allow a wider range of ALC levels!? A simple resistive divider with a clamp would not have created any delays to speak of and would still provide full protection. [and yes - I know that some people will indeed turn their exciter to max and rely on the ALC - and would agree that is just dumb ... ]

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Ria - N2RJ, Elmer

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The details about CAT power control is on page 39.

http://www.expertlinears.com/pdfs/expert_1-3K_manual.pdf
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Gary

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thank you .... I'll still keep an ALC as its purpose isn't for 'routine' power control but rather "stuff happens" (cleaned up the phrase) control... but I stand corrected - thanks again.

g.

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Mark Erbaugh

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Aren't you concerned that the -11v could damage the flex?
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Gary

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its a simple voltage divider and a zener clamp ... I wouldn't connect them without having done this first nor would I recommend anyone doing that. Since I don't know whether or not the 6700 will be damaged, as the their manual seems to suggest ... I'll protect (the protection circuit).
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John - K3MA

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Does PTT also work thru the Flex to USB to SPE interface?  If so how is this enabled?
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Ria - N2RJ, Elmer

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Ptt needs a relay connection as you would normally do for any amplifier (except power genius XL i heard)
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Mark Erbaugh

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My oversight. I did have a phono cable set between TX1 out on the flex and the Relay input on the amp.
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Matt NQ6N

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FWIW there was a thread on the Elecraft reflector about this, and Wayne recommended not using ALC as the primary method of controlling amplifier output with a K3. His response was based on the characteristics of the K3's ALC circuit.  Seemingly the K3's ALC circuit is slow and will result in a fair bit of overdrive (and splatter) when connected to an amp.  

http://elecraft.365791.n2.nabble.com/Question-K3-ALC-w-SPE-Expert-1-3K-FA-amp-tp7600955p7600957.html